Hi mcgill!Wow, I'm impressed you're playing that piece. You must be an excellent pianist!...I know the passage you're talking about. When I played the piece, I didn't really have to develop a "trick" because my hands are so huge, but I'll give it a shot! It was the octaves at the end of that movement that drove me crazy for a while.The hard thing is that your hand is so spread out. When this happens, the fingers lock up and your brain loses track of where they are. When your fingers move your brain keeps way better track of them. You know that childrens' trick where you stick out your 2nd fingers and try to touch them over your head? Most people miss. That's because the fingers are locked and not moving. Now try it while wiggling both fingers--you will suddenly have a new found sense of accuracy.So I think the key here is to move your fingers even though your hand is spread out. Approach the bottom note with the thumb slightly bent, and extend the thumb to play the note, thereby pushing the rest of your hand toward the higher note a tenth above. It'll feel like your fingers are working pretty hard, but keep in mind you don't have to push too hard 'cause it's soft.This is just one attempt. Try it, and if it doesn't work, I'll give you another suggestion. (Another movement I can think of would be like trying to unscrew a wide lid counterclockwise with your thumb and fifth finger. It's a different motion, but something to try. I never run out of ideas )Let me know what happens--if these don't work I'll think of other stuff.